This invention relates to an alpine ski structure and more specifically, it is concerned with high strength fiber reinforcing means positioned generally horizontally in the cross-section of a fiberglass sandwich-structured ski above or in the plane of the compression carrying laminate layer to selectively increase the flexural response and compressive strength of the ski.
The continued popularity of downhill skiing has focused attention on the structure of skis to produce a ski that provides greater responsiveness to the improved skiing techniques being employed by skiers today and the increased speed being achieved as a result of these techniques. This continued popularity has caused the materials used in skis to be changed in response to efforts to develop higher performance skis at lower manufacturing costs. Skis have been made solely from wood, composite wood-plastic materials, as well as entirely from plastics. Skis made entirely from metal have also been manufactured, as well as incorporating metal into composite wood-plastic skis or into all plastic skis. In particular, the advent of high performance wood-fiberglass and fiberglass-plastic foam skis has intensified the skiing industry's efforts to solve the problem of providing a ski constructed of quality materials which give increased ski return rates, increased torsional and flexural stiffness, increased flexural yield strength and a bottom steel running edge with increased impact resistance.
Different approaches have been taken in attempts to solve these problems as higher performance skis have evolved in the ski industry. Initially, skis were made with just a wooden core. A core made of plastic material, such as polyurethane placed within a honeycomb structure formed from aluminum, was employed for a limited time. Historically, skis have been manufactured by laminating, torsion box or reaction injection molding processes. However, because of the higher performance nature of today's skis, these composite skis are subjected to greater flexibility strains which the aforementioned constructions have either failed to withstand or have provided skis which produce a dead sensation to the user. High strength, man-made fibers have been recently incorporated into skis with a fiberglass-sandwich structure to attempt to increase the responsiveness of the ski.
None of the aforementioned structures have provided skis which balance the considerations of high material costs, increased responsiveness, decreased weight, increased structural strength, reproducibility of physical properties in manufacture, and uniform and efficient dispersion of the high strength fibers in the cross-section of the ski during manufacture. Prior ski designs incorporating high strength fibers have inefficiently and randomly placed the fibers during manufacture. This has resulted in a wide variation of physical properties among the final products of skis of supposedly the same design.
The foregoing problems are solved in the design of the present invention by providing in a fiberglass sandwich-structured alpine ski selectively positioned pultruded high strength fiber reinforcing means above or in the plane of the compression carrying laminate.